There are many applications in construction and estimation requiring the remote measurement of a distance, area or volume using multiple points along a surface. In surveying, the capability to locate arbitrary points in space is provided by devices often referred to as total stations or Theodolites. These tripod-mounted devices can measure azimuth, elevation and the distance to very high precision, (millimeters/arc seconds) to establish the location in polar coordinates. They can use precision ruled scales or angle encoders to measure angle and distance can be provided, for example, by optical triangulation. These devices are often expensive and cumbersome, and provide more precision than is necessary in many cases. Their use is not always convenient.
In many instances, a high degree of measurement accuracy to selected points is not required. For example, the measurement of the height, width or area of a physical opening or surface is often required to estimate the area of material to cover a region or to estimate the size of a window or door. As another example, in excavation it is important to estimate the volume of material to be removed from or added to a site. In these instances, a lesser degree of precision is required than in surveying applications. Less cumbersome equipment is also convenient.
Handheld distance measurement devices address this need to some extent. Typical devices use an optical engine to measure distance. For example, the emission, sensing and triangulation of multiple beams can be used to determine the distance of a given point. Other handheld distance measurement devices uses a phase difference optical distance measurement engine. A beam is emitted by the optical distance measurement engine and the reflection of the beam from a target is sensed. The phase difference of the reflected beam relative to the emitted beam is indicative of the distance. Beams of multiple frequencies may be used to improve accuracy. Such optical distance measurement engines or other distance measurement engines of typical handheld devices can provide suitably precise distance measurements when a measurement is taken. However, the control and timing of the measurement is conducted in a manner that often fails to take advantage of the precision offered by the distance measurement engine.
As an example, an interesting class of measurement is the measurement of a distance on level or at a particular angle of elevation relative to level. Typical handheld distance measurement devices include a spirit vial to assist a user in determining level or elevation. A distance measurement on level involves the operator of the handheld distance measurement device interpreting the spirit vial and manually activating the time of measurement. This is a difficult technique to repeat for a given measurement.